Well, there are a few shows with extreme cliffhangers, but the ones that I consider the biggest involve those whose show either end or take a break. If there's an episode in the next week, that's not really a very big cliffhanger compared to those whose cliffhangers happen at the end. It's quite a long wait to figure out what happens, so that drives up the magnitude of it. So I am thinking just about shows that end without much in the way or resolution. That said, here are the shows with the biggest ones: